1. Field of the Invention
The present invention is generally related to a method for controlling an engine and, more particularly, to a method for controlling an engine in which a pseudo throttle position sensor value is determined and used when an actual throttle position sensor signal is not readily available to an engine controller.
2. Description of the Prior Art
Many different types of engine control systems are well known to those skilled in the art. Many engine control methods use a sensor, such as a throttle position sensor, which provides a signal that is representative of the actual angular position of a throttle plate within an air intake manifold. The signal from the throttle position sensor is used by control algorithms as a means to determine the magnitude of air flow into the cylinders of the engine.
U.S. Pat. No. 5,967,861, which issued to Ozawa et al on Oct. 19, 1999, describes a throttle position sensor mounting arrangement for a personal watercraft engine. The throttle valve is positioned within an intake pipe of an intake system of an engine which is positioned in an engine compartment defined by a hull of a watercraft. An output shaft of the engine is arranged to drive a water propulsion device of the watercraft. The intake pipe extends from the engine and is arranged to route air to a combustion chamber of the engine. The throttle position sensor is mounted so as to be shielded by the intake pipe from a source of water within the engine compartment, such as an outlet of an intake duct leading through the hull of the watercraft. U.S. Pat. No. 5,906,524, which issued to Ozawa et al on May 25, 1999, describes a throttle position sensor mounting arrangement for a personal watercraft engine. The throttle valve is positioned within an intake pipe of an intake system of an engine which is positioned in an engine compartment defined by the hull of a watercraft. An output shaft of the engine is arranged to drive a water propulsion device of the watercraft. The intake pipe extends from the engine and is arranged to route air through a combustion chamber of the engine. The throttle position sensor is mounted so as to be shielded by the intake pipe from heat generated by the engine and radiated therefrom and from an exhaust system associated therewith.
U.S. Pat. No. 5,273,016, which issued to Gillespie et al on Dec. 28, 1993, describes a throttle lever position sensor for a two-stroke fuel injected engine. The marine propulsion device comprises a propulsion unit which is adapted to be mounted on a boat and includes a propeller shaft and an internal combustion engine drivingly connected to the propeller shaft. The engine includes an engine block structure having a combustion chamber and defining an air intake passage communicable with the combustion chamber, a throttle plate movably supported by the engine block structure and located in the air intake passage, structure for moving the throttle plate in response to movement of an operator control member, and structure supported by the engine block structure for providing a signal indicating the position of the control member independent of the position of the throttle plate.
U.S. Pat. No. 4,646,696, which issued to Dogadko on Mar. 3, 1987, describes a programmed electronic advance for engines. The spark plug ignition advance control for a multiple cylinder internal combustion engine has a spark ignition circuit associated with each cylinder. The circuit includes a SCR trigger operative to cause the ignition spark. A pulse generator is associated with each cylinder and puts out a control pulse to a latch gate outputting to the ignition circuit. The gate responds to a control pulse to latch in an enabled state. A frequency multiplier receives control pulses from the pulse generator and provides 360 reference pulses for each revolution of the engine. A counter responds to the control pulse to count said reference pulses. A ROM storing ignition timing data corresponding to a throttle position is provided. A throttle position sensor provides a control voltage which is applied to an A/D converter which outputs an address in the ROM and the ROM puts out the number of degrees by which the base throttle advance is to be modified and sets the counter to count said reference pulses to said number. The counter subtracts the counts from the basic advance and outputs a control signal when the correct advance is reached. The firing pulse is applied to the latch gate which causes the SCR trigger to operate. The firing pulse also resets the system to start again for the next cylinder.
U.S. Pat. No. 5,943,996, which issued to Sogawa et al on Aug. 31, 1999, describes a direct injection system for engines. A number of embodiments of direct injected V-type outboard motors is described. In each embodiment, a high pressure pump is driven off of the upper end of the crankshaft and is disposed at a high level in the protective cowling. The drive for the high pressure pump is disposed in the path of air flow from an opening in the protective cowling to the engine induction system. On the other hand, the high pressure pump is out of this air flow to avoid corrosion. Various alternative locations for the components of the engine including specifically the high pressure pump, an alternator, a fuel vapor separator, an ECU control unit, and a fuel injector solenoid driver are disclosed.
U.S. Pat. No. 5,941,743, which issued to Kato on Aug. 24, 1999, describes an engine control system. The engine control for an internal combustion engine powering a water propulsion device of an outboard propelling a watercraft is disclosed. The engine control changes one or more combustion condition parameters of the engine based upon changes in one or more operating conditions of the motor or watercraft which affect the exhaust back pressure of the exhaust in the exhaust system of the engine. The operating conditions may include the motor trim angle, watercraft speed, watercraft posture, transmission position, and engine mount height. The engine control changes a combustion condition parameter such as the air/fuel ration, spark ignition timing, or fuel injection timing to optimize the engine operating performance based upon the detected operating parameter.
U.S. Pat. No.5,868,118, which issued to Yoshioka on Feb. 9, 1999, describes a fuel injection control device for outboard motors for low speed operation. A fuel injection control device for outboard motors optimizes the air-fuel ratio when trim is applied to the outboard motor, especially those with two cycle engines. In such an outboard motor, engine, speed, throttle setting, engine boost pressure, engine temperature, intake air temperature, and/or other variables are detected and a basic fuel injection volume determined. Fuel is supplied to each of the engine's cylinders according to the detected values. A trim angle detecting means is used to indicate trim angle. During low speed operation, the trim angle is detected, and the magnitude of a change in the trim angle is calculated. The magnitude of the change in the trim angle is sued to estimate the residual fuel volume within the engine. The estimated value is used to apply correction to the basic fuel injection volume following the change in trim angle. As a result, during low speed operation, an optimal air-fuel ratio can be obtained when the trim of the outboard device is changed.
U.S. Pat. No. 5,862,794, which issued to Yoshioka on Jan. 26, 1999, describes a fuel injection control device for outboard motors. In an outboard motor having a fuel injected two cycle engine, engine speed, throttle setting, engine temperature and/or other variables are detected and a basic fuel injection volume determined. Fuel is supplied to each of the engine's cylinders according to the detected values. When the engine is operating at a high speed, trim angle and vessel speed are detected. The trim angle and vessel speed are used to correct the basic fuel injection volume determined before high speed operation of the engine is detected.
U.S. Pat. No. 5,852,998, which issued to Yoshioda on Dec. 29, 1998, describes a fuel injection control device for outboard motors. In an outboard motor having a fuel injected two cycle engine, engine speed, throttle setting, engine boost pressure, and/or other variables are detected and a basic fuel injection volume determined. Fuel is supplied to each of the engine's cylinders according to the detected values. When the engine is stopped, information about the operating conditions of the engine before the engine was stopped are saved in a memory of a controller. These saved values represent the residual fuel volume left in the engine's cylinders at a subsequent startup of the engine. The saved values are used to correct the basic fuel injection volume determined at startup by the controller.
U.S. Pat. No. 5,827,150, which issued to Mukumoto on Oct. 27, 1998, describes an engine control system having shift assist with fuel injected during ignition cutoff while shifting. A marine propulsion engine control system wherein the control includes an arrangement for slowing the speed of the engine by disabling certain cylinders in the event of an abnormal engine running condition is disclosed. Also, an arrangement is provided for slowing the speed of the engine if a change speed transmission for driving the propulsion shaft by the engine offers more than a predetermined resistance to shifting. The controls are interrelated so that the engine protection control predominates. That is, if the engine is in protection control mode and the operator attempts a shift and more than a predetermined resistance is felt, the shift control routine will not be initiated to effect any additional engine speed reduction. In addition, when the engine speed is reduced, fuel is continued to be supplied by the fuel injectors to avoid backfiring, stalling, and uneven running. When rapid deceleration is called for the spark advance is rapidly retarded but fuel injection amount is gradually decreased.
U.S. Pat. No. 5,813,374, which issued to Chasteen on Sep. 29, 1998, describes a two cycle engine with electronic fuel injection. The fuel injection system for two cycle engine comprising an air manifold, a throttle valve, a fuel injector, a fuel supply system including a fuel pump, a battery voltage sensor, an air temperature sensor, an engine speed sensor, a timing sensor, a barometric pressure sensor, a throttle position sensor, a first data processor for receiving and processing sensing signals for determining fuel injector duration and timing and fuel pump operating speed, a first data processor temperature sensor for sensing the relative temperature of certain electronic components in the first data processor, a heater operatively associated with the first data processor electronic components for selectively heating the electronic components, and a second data processor operable independently of the first data processor for receiving an electronic component temperature sensing signal and for generating a control signal to the heater responsive thereto for heating the components when the temperature thereof is below a predetermined minimum value is described.
U.S. Pat. No. 5,730,105, which issued to McGinnity on Mar. 24, 1998, describes an idle control for an internal combustion engine. A method is described for controlling fuel injection in an internal combustion engine including a crankshaft, a fuel injector, and a control unit for outputting a signal causing a fuel injection event, with a minimum time delay between the output of the signal and initiation of the fuel injection event, the method comprising the steps of sensing crankshaft position, outputting the signal, and providing an additional time delay between the output of the signal and initiation of the fuel injection event so that the signal must be output at an earlier crankshaft position than would be necessary without the additional time delay, whereby changing crankshaft speed has a greater effect on the difference between the desired crankshaft position of the fuel injection event and the actual crankshaft position of the fuel injection event.
U.S. Pat. 5,666,935, which issued to Kato on Sep. 16, 1997, describes a fuel injection control system for an engine. A feedback control system for an internal combustion engine, particularly as utilized in an outboard motor, is disclosed. An oxygen sensor outputs a signal indicative of the fuel-air ratio for controlling the charge forming system of the engine to maintain the desired fuel-air ratio. A series of filters, each tuned for a different frequency and a different engine speed, are interposed between the sensor and the control for reducing the effect of noise.
U.S. application Ser. No. 09/422,614 (M09367) which was filed by Suhre on Oct. 21, 1999 and assigned to the assignee of the present application, describes an engine control system using an air and fuel control strategy based on torque demand.
The control system for a fuel injected engine can comprise an engine control unit (ECU) that receives signals from a throttle handle that is manually manipulated by an operator of a marine vessel. The engine control unit can also measure engine speed and various other parameters, such as manifold absolute pressure, temperature, barometric pressure, and throttle position. The engine control unit then controls the timing of fuel injectors and the injection system and also controls the position of a throttle plate. No direct physical connection is provided between the manually manipulated throttle handle and the throttle plate. All operating parameters are either calculated as a function of ambient conditions or determined by selecting parameters from matrices which allow the engine control unit to set the operating parameters as a function of engine speed and torque demand, as represented by the position of the throttle handle.
U.S. patent application Ser. No. 09/264,610, which was filed by Suhre et al on Mar. 9, 1999 and assigned to the assignee of the present application, discloses an engine guardian protection control system. The engine control system is provided which measures one or more engine condition indicators, such as engine pressure, engine temperature, battery voltage or oil level in a reserve tank. This information is used to calculate a maximum magnitude for an engine operating characteristic such as output power. By determining the torque of the engine and its operating speed, an output power can be calculated and compared to an output power maximum limit that is determined as a function of the engine condition indicator. By comparing these two values, the control system can cause the engine to operate at or below the maximum allowed magnitude. As a result, the output power of an engine is correspondingly reduced to changes in the monitored engine condition. As a result, decreasing engine coolant pressures or increasing engine temperatures can cause the control system to reduce the maximum output power of the engine regardless of the throttle position commanded by the marine vessel operator.
The patents described above are hereby explicitly incorporated in the description of the present invention.
Many different types of control systems require an input that is representative of the actual position of a throttle plate within an air intake manifold system. Throttle position sensors are typically used to provide this representative signal and are typically attached to a shaft about which the throttle plate rotates. Throttle position sensors can incorporate potentiometers or Hall-effect transducers. When a throttle position sensor fails, some control systems immediately reduce the maximum operating speed of the engine to a speed that is slightly greater than idle speed to allow a marine vessel to return to port. It would therefore be significantly beneficial, in marine propulsion systems, if a system could be provided in which the failure of a throttle position sensor would not require that the marine vessel be operated at or near idle speed. Instead, it would be beneficial if the operator of the marine vessel could return to port at speeds greater than idle speed.